Ghost Fusion

Clearer Effect.

During either player's turn: You can Fusion Summon 1 monster from your Extra deck if all of its materials are in your Graveyard and they have been destroyed since the beginning of your last turn. You cannot use the materials for another Fusion Summon by this card. The summoned Fusion Monster cannot be destroyed in battle, as long as it remains face-up.

Only graveyard? I was thinking of Schrodingering the materials and then use Ghost Fusion.

Oh, yeah.

During either player's turn: You can Fusion Summon 1 monster from your Extra deck if all of its materials are in your possession and they have been destroyed since the beginning of your last turn. You cannot use the materials for another Fusion Summon by this card. The summoned Fusion Monster cannot be destroyed in battle, as long as it remains face-up.